Why the World May Well End (Though Not on Dec 21)

The world did not end on Dec. 21. But for humans, given current trends, the world may indeed end some time in the next 10,000 years. Here is why.

Humans gained supremacy in the food chain, through five evolutionary accidents: large brains, walking upright, the human thumb, cooking their food with fire, and giving birth to babies very early in their development.

* The first human beings, who appeared 2.5 million years ago, had extra-large brains. The average brain size for a 55 kg. (121 lb.) mammal is 180 cc’s. For a human, it is 6-7 times larger: 1,200 – 1,400 cc’s. At rest, these large brains consume about 25% of the body’s energy consumption. It is not entirely clear to biologists what advantage these large brains conferred on early humans, enabling them to survive to reproduce.

* Human babies enter the world through the relatively narrow pelvis of women (narrower than that of female mammals). As a result, so that their large heads can get through the narrow passage, human babies are born at an earlier stage of their development than other mammal babies. (Baby zebras can run soon after birth, for example. It takes human babies about 18 months). This implies a longer infancy for humans, during which human babies learn a great deal from their parents and family.

* Humans walk upright. This is relatively inefficient, because it takes more energy to support the enlarged human head, and is partly why female humans have narrow womb passages. But it has advantages.

* The human hand is another advantage. The opposing thumb enables many delicate operations, including the use of tools.

* Humans cook their food. This enables them to eat a very wide variety of foods. Perhaps the enlarged human brain made this possible, and also made possible agriculture, growing our own food in order to cook it. This required humans to tame and domesticate the use of fire.

And here is the irony. It is that same fire, the burning of fossil fuels, in internal combustion engines, that may end the dominance of humans at the top of the food chain. Climate change may doom us. It may have been a happy accident that made us humans, weaker than other mammals, clumsy, with needlessly big brains, dominate the food chain. That accident may be short-lived, only 80,000 years or so. We may have huge brains, but we were not smart enough to use them, to learn how to live on our planet in harmony with Nature and other creatures. We kill mammals and eat them, wasting six of every seven calories needed to do so. We ruined our planet and homo sapiens may pay the price.

In his wonderful 2012 book From Animals into Gods: A Brief History of Humankind, Israeli historian Yuval Harari notes that about 100,000 years ago, Homo sapiens was still an insignificant animal minding its own business in a corner of Africa. Our ancestors shared the planet with at least five other human species, and their role in the ecosystem was no greater than that of gorillas, fireflies, or jellyfish. Then, about 70,000 years ago, a mysterious change took place in the mind of Homo sapiens, transforming it into the master of the entire planet and the terror of the ecosystem.

Will humanity survive for another 10,000 years, after wrecking the ecosystem? Stay tuned.